The National Transportation Safety Board (NTSB) has released an investigation report on the the towing vessel Susan K that struck the center bridge pier on the Natchez-Vidalia Bridge in April 2023.
The incident
On April 23, 2023, about 2242 local time, the towing vessel Susan K was pushing 25 barges downbound on the Lower Mississippi River when the tow struck the center bridge pier on the Natchez-Vidalia Bridge, which connects the cities of Natchez, Mississippi, and Vidalia, Louisiana.1 One barge sank, and two other barges were damaged; the Susan K was undamaged. No pollution or injuries were reported. Damage to the barges and cargo was estimated at $2 million.
Analysis
After maneuvering the Susan K tow through a gradual bend in the Mississippi River, the captain of the towing vessel intended to steer the tow through the western (right-descending-bank side) channel under the Natchez-Vidalia Bridge. However, he told investigators that he “wasn’t paying attention” to what he was doing, and, consequently, the tow was too far toward the left descending bank to transit through the western channel.
The captain attempted to steer the tow through the eastern channel, but the tow struck the bridge pier dividing the channels. There was no evidence that the captain was fatigued, impaired, or distracted before or during the casualty. The captain had decades of experience captaining towing vessels and maneuvering tows, and he had steered tows through the Natchez-Vidalia Bridge hundreds of times. There was nothing unusual about the transit or approach that would have heightened the captain’s awareness or vigilance, such as adverse weather or river conditions, vessel traffic, or mechanical issues with the vessel. Reflecting on the casualty, the captain said, “You get complacent sometimes when you do something so many times.”
Complacency can cause attention lapses that arise from repetition, familiarity, or comfort with a particular task. Repetition and familiarity reduce the required level of cognitive effort required to execute such tasks—even complex, skill-based tasks—increasing the susceptibility to attention lapses or distraction. Attention lapses can delay the detection of subtle abnormalities, affecting an operator’s reaction time to and identification of developing hazards.
Due to complacency, the Susan K captain was inattentive as the tow approached the bridge, which resulted in the tow being out of position for his intended route under the bridge. His awareness of the situation came too late to avoid striking the bridge pier.
Probable Cause
The National Transportation Safety Board determines that the probable cause of the contact of the Susan K tow with the Natchez-Vidalia Bridge was the captain’s complacency, which resulted in his inattention to the tow’s position as it approached the bridge.
Lessons learned: Fighting Complacency
Repetition and monotony can cause even the most experienced and skilled mariner to become complacent and lose situational awareness. Developing strategies that help maintain focus is a good practice.
These strategies may include continuous scanning of instruments and surroundings outside the wheelhouse, strict adherence to procedures, eliminating distractions, changing position or moving (standing up or walking around), and getting enough sleep and exercise.
